Our question is whether it is possible, by means of (18)F Fluorodesoxyglucose-Positron-Emission-Tomography-Computertomography (FDG-PET-CT) data created in line with the diagnostics of chronic osteitis, to undertake a navigation for the treatment of the focus of osteitis.

Within the scope of an experimental examination, the focus of osteitis at an animal bone model (pork) has been simulated. The animal bone was prepared with injection of FDG via three 2.5 mm drill holes into the bone marrow. For further investigation the FDG was injected undiluted, mixed with pigment and with radiopaque contrast medium.

Using FDG, a PET-CT dataset at the primed animal bone model has been created. For matching the position of the artificial FDG-focus and the virtual displayed position two cortical screws were placed close to the FDG-focus in the cortical bone. Two X-Ray shots in different positions were taken from the region of interest. The referencing of the dataset was achieved with CT-fluoro-matching. Finally, the accuracy of the image of the navigated instrument on the navigation display has been compared with the optical controlled actual placement of the simulated position of the focus of osteitis. The bone was sawed for the final check of the position of the FDG spot in relationship to the anatomical landmarks.

The examination demonstrated that with the available navigation system a PET-CT dataset could be identified. The matching of the CT-dataset with the geometry of the animal bone model was realised with CT-fluoro-matching software.

The verification of the image accuracy on the navigation screen did not show any deflection of the actual placement of the navigated instrument, because the position of the simulated focus of osteitis through the drilled canal was known. The experimental examination described above showed that PET-CT data can be imported into a conventional optical navigation system and can be edited for referencing purposes. It was possible to match the CT-dataset with the fluoroscopic images of the image intensifier. The optical verification of the accuracy did not show any deflection of the displayed position of the navigated instrument compared to the actual placement of the simulated focus of osteitis. The investigation shows sufficient threshold of the animal bone for visualisation with the navigation system.

Since the PET-CT data provide evidence about the activity of a pathological focus, in addition to the information about localisation, the navigated rehabilitation of foci of osteitis in long hollow bones appears possible. For successful treatment and salvage of chronic osteitis the implementation of navigated surgical tools can reduce the dimension of the surgical approach and damage of bone without reduction of the surgical goal.

Further clinical applications must determine whether the possibilities established experimentally can be implemented effectively in practice.